Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Grasshopper love songs give insight into sensory tuning

04.08.2005


As anyone whose nerves have been jangled by a baby’s howl or who have been riveted by the sight of an attractive person knows, nature has evolved sensory systems to be exquisitely tuned to relevant input. A major question in neurobiology is how neurons tune the strength of their interconnections to optimally respond to such inputs.



Neuronal circuitry consists of a web of neurons, each triggering others by launching bursts of neurotransmitters at targets on receiving neurons to produce nerve impulses in those targets. Neurons adjust the strength of those connections adaptively, to amplify or suppress connections. Some four decades ago, a general principle called the "efficient coding hypothesis" was formulated, holding that sensory systems adjust to efficiently represent the complex, dynamic sounds, sights, and other sensory input from the environment.

Writing in the August 4, 2005, issue of Neuron, researchers led by Christian K. Machens of Cold Spring Harbor Laboratory and Andreas Herz of Humboldt-University Berlin describe experiments with grasshopper auditory neurons that reveal new details of such sensory coding. Their findings show that "optimal stimulus ensembles" that trigger the neurons differ from those the grasshopper hears in the natural environment but largely overlap with components of natural sounds found in mating and mate-location calls.


In their experiments, the researchers first played various snippets of white noise to isolated grasshopper auditory nerves and measured the electrophysiological signals reflecting the reactions of the auditory neurons to those sounds. These experiments revealed the distribution of stimuli called the "optimal stimulus ensemble" (OSE) that allowed the neurons in the system to perform optimally.

Once the researchers had characterized the OSE, they then analyzed how this measure compared to the neuronal response to natural sounds--including environmental sounds like the rustling of grass and insect communication signals such as grasshopper or cricket mating calls.

They found that the OSEs of the receptors particularly matched characteristic features of species-specific acoustic communication signals used by grasshoppers to attract mating partners.

"Hence, instead of maximizing the average information gained about natural stimuli, the receptors appear to maximize the information gained about specific, but less often occurring aspects of the stimuli," concluded the researchers. "This result suggests that an organism may seek to distribute its sensory resources according to the behavioral relevance of the natural important stimuli, rather than according to purely statistical principles.

"For instance, if a few important stimuli within the natural environment need to be encoded with high precision, a large part of a system’s coding capacity could be designated to encode these stimuli. Consequently, it may well be that even small subensembles strongly influence the coding strategy of sensory neurons. In this case, the optimal stimulus ensemble will not match the ensemble of all natural stimuli encountered by the particular species."

The researchers also concluded that "We therefore suggest that the coding strategy of sensory neurons is not matched to the statistics of natural stimuli per se, but rather to a weighted ensemble of natural stimuli, where the different behavioral relevance of stimuli determines their relative weight in the ensemble."

Machens, Herz, and their colleagues also concluded that their analytical technique could yield broader insight into the evolution of sensory circuitry.

"Our approach presents a systematic way to uncover potential mismatches between the statistical properties of the natural environment and the coding strategy of sensory neurons. In turn, these discrepancies might improve our understanding of the evolutionary design of the specific sensory system," they wrote.

Heidi Hardman | EurekAlert!
Further information:
http://www.cell.com
http://www.neuron.org

More articles from Life Sciences:

nachricht Bacteria as pacemaker for the intestine
22.11.2017 | Christian-Albrechts-Universität zu Kiel

nachricht Researchers identify how bacterium survives in oxygen-poor environments
22.11.2017 | Columbia University

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Nanoparticles help with malaria diagnosis – new rapid test in development

The WHO reports an estimated 429,000 malaria deaths each year. The disease mostly affects tropical and subtropical regions and in particular the African continent. The Fraunhofer Institute for Silicate Research ISC teamed up with the Fraunhofer Institute for Molecular Biology and Applied Ecology IME and the Institute of Tropical Medicine at the University of Tübingen for a new test method to detect malaria parasites in blood. The idea of the research project “NanoFRET” is to develop a highly sensitive and reliable rapid diagnostic test so that patient treatment can begin as early as possible.

Malaria is caused by parasites transmitted by mosquito bite. The most dangerous form of malaria is malaria tropica. Left untreated, it is fatal in most cases....

Im Focus: A “cosmic snake” reveals the structure of remote galaxies

The formation of stars in distant galaxies is still largely unexplored. For the first time, astron-omers at the University of Geneva have now been able to closely observe a star system six billion light-years away. In doing so, they are confirming earlier simulations made by the University of Zurich. One special effect is made possible by the multiple reflections of images that run through the cosmos like a snake.

Today, astronomers have a pretty accurate idea of how stars were formed in the recent cosmic past. But do these laws also apply to older galaxies? For around a...

Im Focus: Visual intelligence is not the same as IQ

Just because someone is smart and well-motivated doesn't mean he or she can learn the visual skills needed to excel at tasks like matching fingerprints, interpreting medical X-rays, keeping track of aircraft on radar displays or forensic face matching.

That is the implication of a new study which shows for the first time that there is a broad range of differences in people's visual ability and that these...

Im Focus: Novel Nano-CT device creates high-resolution 3D-X-rays of tiny velvet worm legs

Computer Tomography (CT) is a standard procedure in hospitals, but so far, the technology has not been suitable for imaging extremely small objects. In PNAS, a team from the Technical University of Munich (TUM) describes a Nano-CT device that creates three-dimensional x-ray images at resolutions up to 100 nanometers. The first test application: Together with colleagues from the University of Kassel and Helmholtz-Zentrum Geesthacht the researchers analyzed the locomotory system of a velvet worm.

During a CT analysis, the object under investigation is x-rayed and a detector measures the respective amount of radiation absorbed from various angles....

Im Focus: Researchers Develop Data Bus for Quantum Computer

The quantum world is fragile; error correction codes are needed to protect the information stored in a quantum object from the deteriorating effects of noise. Quantum physicists in Innsbruck have developed a protocol to pass quantum information between differently encoded building blocks of a future quantum computer, such as processors and memories. Scientists may use this protocol in the future to build a data bus for quantum computers. The researchers have published their work in the journal Nature Communications.

Future quantum computers will be able to solve problems where conventional computers fail today. We are still far away from any large-scale implementation,...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Ecology Across Borders: International conference brings together 1,500 ecologists

15.11.2017 | Event News

Road into laboratory: Users discuss biaxial fatigue-testing for car and truck wheel

15.11.2017 | Event News

#Berlin5GWeek: The right network for Industry 4.0

30.10.2017 | Event News

 
Latest News

Corporate coworking as a driver of innovation

22.11.2017 | Business and Finance

PPPL scientists deliver new high-resolution diagnostic to national laser facility

22.11.2017 | Physics and Astronomy

Quantum optics allows us to abandon expensive lasers in spectroscopy

22.11.2017 | Physics and Astronomy

VideoLinks
B2B-VideoLinks
More VideoLinks >>>